Since 1988 the CIMMYT SHL has been officially authorized by DGSV (Direccion General de Sanidad Vegetal) to carry out the quarantine procedures on seed introductions coming into Mexico and CIMMYT, and in April 2007 the SHL obtained accreditation under standard ISO/IEC 17025: 2005, “General requirements for testing and calibration laboratories”, as required by the Mexican government. An official DGSV inspector is assigned exclusively to CIMMYT to assist with thorough and timely seed inspection and importation.

All seed brought into CIMMYT, without exception, must be subjected to quarantine procedures in the Seed Health Laboratory.

The pathogen detection and identification flowchart is described below:

All maize seed, both entering and leaving CIMMYT, must pass through the seed health laboratory. All seed undergoes the same set of testing procedures, although the key target pathogens vary between incoming and outgoing seed depending on relevant quarantine regulations.

CIMMYT generally uses well-established test procedures that may be found in any standard reference on seed health. The filter wash test is somewhat specialized, and the procedure are given in CIMMYT Seed Health Manual.

Seed wash filter test, which reveals the presence of fungal spores—including bunt teliospores (Tilletia spp.), smut spores (Urocystis and Ustilago spp.), and downy mildew oospores (Peronosclerospora and Sclerophthora spp.)—and of nematode cysts. This test takes around three hours, although large volumes of samples make take longer. Composite samples of outgoing seed may be used (with rechecking of individual lines in the event of a positive result).

Freezing blotter test, which reveals the presence of imperfect fungi carried by seed and takes two weeks.

Greenhouse germination test, for the expression, and thus detection, of seed-borne pathogens, and to check seed viability. This test takes three weeks. If symptoms appear on seedlings, further testing to identify the causal pathogen is carried out (i.e. ELISA or other tests).